Aside from my college books, I rarely marked any physical books up. When I went to ebooks on tablets from hardcopy, briefly, I got into notes and whatnot with MoonReader for a couple years (like 2013-2015). Don't see any point in it now. Mostly just questions, and always about non-fiction.

What's annoying are people who want other people to find their notes in books (and even sell them for the ego aspect).